Composting

Traditional composting involves creating a fermentation process from wet and dry organic waste. The compost produced fertilizes the soil and plants.

Contents

Used by nature since the dawn of time

Fortunately, this age-old method of transforming organic matter is making a comeback, as its advantages are numerous. Composting, which is practised exclusively in the garden, consists of accumulating green (garden) waste with kitchen waste in a heap on the ground, or in a commercial or home-made composter, which needs to be stirred and watered regularly.

The alternation of organic and carbon-based waste (straw, wood, cardboard, etc.) creates a chemical combustion, known as the thermophilic or hygienization phase: the temperature rises to 70°C and then falls again. This natural combustion is largely due to the action of the compost's highly varied fauna (bacteria, fungi, insects and compost worms), which ascends from the soil towards the waste. Compost is the result of this ingenious combustion.

From humus to people: let's find our roots!

We're talking roots, so let's talk etymology : the common noun humus comes straight from the Latin humus, meaning soil, earth, a term itself to be related to the Greek χαμαί, meaning down to earth. By extension, humus became the adjective humanus, literally of the earth, which refers to humankind. Humanus has also given us the homunculus: the poor little man... who has lost his roots, his link to the earth by concreting over his environment, turning agricultural fields into suburbs and ringing the planet with roads and freeways, for an artificial takeover of his surroundings..

And yet, without humus, there is no human race, because there are no plants. And without humus, there are no roots to tie us to something larger than ourselves...

Humus, an endangered source of life
by humankind

Humus comes from the decomposition of organic plant and animal waste by detritivorous organisms and micro-organisms, including bacteria, fungi and arthropods. And let's not forget the planet's precious intestines (Aristotle) : earthworms. They are nature's and humankind's most faithful allies.

Humus, the organic component of soil, gives it its black color. It brings warmth out of winter and allows nature to continue its cycle. Humus is essential to the development of plants, as it plays a vital role in the soil's physical and chemical characteristics. The quality of our environment depends on the harmony of these factors.

Humus is a colloid. It is one of the elements that "glue" other soil elements together. It thus contributes to soil structure. The decomposition of humus releases mineral elements that can be directly assimilated by plants, including nitrogen and other nutrients essential for plant growth (phosphorus, potassium, etc.).

There are several types of humus, depending on the climate. Humus' main contribution to soil fertility is its role as a reservoir for both water and nutrients. Humus is a living substance, thanks to its micro-organisms, which need a regular supply of organic matter to continue multiplying and giving life to the soil.

Humus combines with clay to form the clay-humus complex. The bond between clay and humus is achieved by the action of earthworms. Clay protects humus against microbial attack.

What farming practices
to preserve humus ?

Before practice, there's the basic axiom : The earth is alive !

Whatever the practice, it must protect and promote life in all its forms. Secondly, it must be natural, without the addition of synthetic chemicals. Primum non nocere, "above all, do no harm", is lesson No. 1 from soil scientist Gérard Augé (see article Bio Contact No. 146 - April 2005 "La bio, une précieuse alliée de la terre et de l'eau").

Intense ploughing has totally asphyxiated our soils... As the latter are totally destructured, episodes of heavy rainfall displace the soil's nutritive elements, which are then no longer available for plant growth. In addition, the frequency of heavy winds could encourage soil erosion and the loss of humus. Nutrients would be further displaced. However, the richer the soil is in humus, the more difficult it is to erode it and displace its nutrients.

Simple practices can be found in biodynamic and organic farming:

Mulching (protective covering)

Who's talking about burning green waste ? Everything can be recycled in the garden ! Shrub and hedge prunings, straw and clippings protect the soil and plant roots from the cold of winter. They provide organic matter for the spring, decomposing while encouraging the activity of micro-organisms and earthworms. Mulching in layers of 5 to 10 cm is traditionally used for market gardening, but also for window boxes and flowerbeds. It retains moisture and prevents undesirable weeds (bindweed, thistles, quackgrass, etc.) from growing, as the seeds thus covered are deprived of light.

Some crops have cleansing effects

potatoes by lightening the soil structure, rye against quackgrass and oats against thistles. Repeated mowing in summer can also get rid of certain invasive plants by preventing them from replenishing their reserves: alfalfa mowed for 3 years helps to control thistle and bindweed.

Moderate tillage

Humus must be preserved with tools that do not damage it (such as the grelinette and hoe). Allowing earthworms to do the work of ploughing ensures the soil's capacity to absorb and resist pollution, and improves aeration.

Plant preparations

are essential allies for gardeners and farmers. We're all familiar with nettle, comfrey, horsetail and onion purins, which accelerate the composting of organic matter, nourish the soil and prevent and cure diseases and pest attacks. These preparations are widely available, and many books offer effective recipes. They can also be found ready-prepared in the form of dissolving powders. Other biodynamic preparations, such as horn dung, known as "500", promote soil structure, microbial activity and humus formation. There are 6 such biodynamic preparations (see Bio Contact N° 133 - February 2004 - "Biodynamic agriculture to save the earth", p.22).

False seeding

this technique consists in preparing the soil in the same way as before sowing, by working it finely, and leaving the "weed" seeds to germinate. In the botanical sense, there are no "weeds", but rather weeds. When the seedlings have emerged, the soil is tilled again to prepare for sowing or to make a new false seed, thus destroying the weeds. The time interval between the first and second tillage operations should encourage a maximum number of seedlings to emerge, to ensure the success of the technique. Thanks to rapid emergence, the space left for weeds is limited and competition works in the crops' favor.

Contributing to and caring for organic matter

this contribution can be made by composting your garden waste, known as green waste, and your kitchen waste in piles in the garden or in a composter. Vermicomposting is as educational, ecological and fun as it is simple to use. It's perfect for those who want to put their kitchen waste to good use in their apartment, thanks to the incessant work of earthworms (they never sleep!) and produce a better-quality solid and liquid soil improver for all plants.

What can you compost ?

All moist organic matter

kitchen waste (raw and cooked fruit and vegetable peelings, tea bags) and wet green waste (grass clippings and leaves).

All carbonic matter

i.e. dry: dry garden waste, shredded branches, paper, cardboard, coffee and coffee filters, eggshells (crushed, they are more easily assimilated).

Note also that

Meat and fish will decompose, but remember to cover them well with carbonaceous matter to avoid nuisance. Citrus fruits (lemons, oranges and grapefruits) contain strong essences that can repel certain composting organisms. Cut them up carefully before adding them. Fats, oils and other sauces can "suffocate" the system, so use them sparingly. Animal excrement is not recommended, as it can carry disease or parasites, and the process takes much longer. Plastics, glass and metals are obviously to be avoided!

How to compost

1. The first important step is to place the composter or heap in an area of partial shade, ideally on drained soil. Choose a convenient location that's accessible all year round.
2. You can turn over the soil where you want to place the composter/compost bin.
3. Cover the bottom with a row of small branches and dead leaves. This will allow air to circulate and improve drainage.
4. Alternate organic and carbonic residues to ensure balanced fermentation.
5. Add "finished" compost. This speeds up the composting process. These are also available from garden centers.
6. Stir the pile to aerate it and water it if it seems a little dry. Otherwise, turn it over after 6 months.
7. Composting is most effective when the pieces of organic matter are small. Weeds and residues should be shredded or ground. Don't add a thick layer of just one type of waste. Spread your fresh waste well, then cover with a layer of dry waste.

What's the difference between worm composting and composting?

Vermicomposting (also known as cold composting, as there's no need to heat up the compost) can be carried out directly in the home, using compost worms. It's an odorless process. Vermicomposting is faster than composting. The resulting vermicompost is stable and directly assimilated by plants, which find in it everything they need, not only to grow spectacularly, but also to resist attacks from parasites and disease.

Vermicomposting is the ideal solution for local biowaste management when you don't have the space to compost. But the two processes are totally complementary!

To find out more, read our article on the differences and complementarities between composting and vermicomposting

Composting and vermicomposting,
guarantee soil fertility

In nature, humus can take several years to form. By making compost or vermicompost, we create the ideal conditions for faster results. It's also an easy way to reduce the amount of waste produced in the kitchen or garden by a third.

Composting takes place in the garden, in piles or in a composter. It's a natural process in which thermophilic bacteria raise the temperature (fermentation), thereby destroying pathogenic germs, disease carriers and parasites.